Lawyers for WikiLeaks founder Julian Assange have asked the British Supreme Court to reopen the appeal against his extradition to Sweden.

Last month, the court rejected Mr Assange's last-ditch appeal against extradition to Sweden, where he is wanted for questioning over sexual assault allegations.

The court, which is Britain's highest, handed down its decision in the 18-month legal marathon after rejecting Mr Assange's argument that the Swedish prosecutor who issued the arrest warrant for him was not entitled to do so.

Mr Assange's lawyers have now challenged the validity of the decision and, in an unusual move, have asked the top court to reopen the case.

Lawyer Dinah Rose asked for 14 days to consider whether to apply to reopen the case on the grounds that the judgment referred to material not mentioned during the appeal hearing in February.

A spokesman for the Supreme Court says the justices will consider the application.

They can choose to reject the challenge, ask for written submissions, or hold a new hearing.

"Lawyers for Julian Assange have lodged papers to apply to reopen the appeal, as expected, for the reasons set out in the hearing," the spokesman said.

A lower court in Britain initially approved Mr Assange's extradition to Sweden in February 2011.

An appeal to the High Court was rejected in November, but Mr Assange subsequently won permission to appeal to the Supreme Court, which heard two days of complex arguments in February.

Mr Assange's supporters fear he will be extradited to the US if he is taken to Sweden.

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